Many forms of physical media require both mass-production and end-user personalization. For example, identity cards may need to be produced for very large population pools, yet every individual card has to uniquely identify the person carrying the card. The high-volume manufacturing phase may be performed on relatively expensive equipment because the equipment cost may be amortized over very large production runs. On the other hand, the end-user personalization may be preferably carried out at customer locations in relatively low volumes, thus, requiring much lower equipment costs.
For many identity cards, security of all information on the card, whether digitally recorded or physical features of the card, is of paramount importance. The security is sometimes tied to some features that reveal whether the media has physically been tampered with. One mechanism for thwarting attempts to tamper with identity cards is lamination. By securing the physical media in a lamination layer that may not delaminated without destroying the physical pristineness of the media goes very far to protect the security integrity of media.
One very important mechanism for tying an individual to an identity object is the placement of a person's photograph on the identity object. Driver's licenses, passports, identity cards, employee badges, etc., all usually bear the image of the individual to whom the object is connected.
Laser engraving provides one prior art technique for personalizing an identity card post-issuance with a photograph. FIG. 1 is a perspective-exploded view of the various layers that make up such a prior art identity card 50. The identity card 50 may include a laser-engravable transparent polycarbonate layer 57. By selectively exposing an image area on the card with a laser, specific locations in the polycarbonate layer 57 may be rendered black, thereby producing a gray-scale image.
Traditionally polycarbonate (PC) ID products have been personalized using laser-engraving technology. This is based on a laser beam heating carbon particles inside specific polycarbonate layers to the extent that the polycarbonate around the particle turns black. While the particles could be chosen to be something else than carbon, it is the intrinsic property of polycarbonate that creates the desired contrast and number of gray levels to produce, for example, a photograph. The gray tone is controlled by the laser power and speed of scanning across the document. This technology is standard on the ID market. However, a limitation of this technique is that color images may not be produced in that manner.
In certain markets and applications it is desirable to have identity cards with color images.
Traditionally color photographs have been placed in identity cards using Dye Diffusion Thermal Transfer (D2T2) technology, which has been available for PVC and PET products. Recently the development in the D2T2 technology has made it possible to color personalize also polycarbonate cards. This technology requires a smooth printed surface and the printed image must be shielded with an overlay film, which can also be holographic type. Gemalto S/A of Meudon, France has developed a desk-top D2T2 solution which has been available on the market since the autumn 2007.
A drawback to surface printed color personalization is that it is not as secure as the laser engraved photos and data that are situated inside the polycarbonate layer structure as illustrated in FIG. 1.
In another prior art alternative, a color image may be produced using digital printing before the product is collated. This allows for high quality images placed on identity cards. Yet this technology has many drawbacks: the personalization and card body manufacturing must happen in the same premises, which furthermore typically have to be in the country of document issuance because governmental authorities dislike sending civil register data across borders, the color printed photographs prevent the PC layers from fusing to each other, and if any of the cards on a sheet is maculated in further production steps, the personalized card must be reproduced from the beginning of the process leading to a highly complicated manufacturing process.
U.S. Pat. No. 7,368,217 to Lutz et al., Multilayer Image, Particularly a Multicolor Image, May 6, 2008 describes a technique in which color pigments are printed on collated sheets and each color may be bleached to a desired tone using a color sensitive laser.
From the foregoing it will be apparent that there is a need for an improved method to provide a mechanism for placing images on identity cards and the like using a mechanism that produces secure tamper proof color images during a personalization phase using inexpensive customer-premises equipment.
In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components or by appending the reference label with a letter or a prime (′) or double-prime (″). If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label appended letter, or prime.